1. Field of the Invention
This invention generally relates to animal products for human consumption. The invention provides low cholesterol animal products for human consumption as food. Specifically, the invention provides methods for producing low cholesterol animal products by supplementing animal feed with microbial cultures containing hypocholesterolemic compounds and animal products produced using the methods. Methods for reducing serum cholesterol in humans and animals are also provided.
2. Background of the Related Art
Cholesterol is an essential constituent of cell membranes in humans and serves as a starting material for the synthesis of important biological compounds such as steroid hormones and bile acids. However, high serum cholesterol levels, termed hypercholesterolemia (more than 200 mg/dL of blood cholesterol), are a major risk factor for coronary artery disease, which leads inter alia to myocardial infarction. Coronary artery disease is the leading cause of human mortality in the United States and in many other developed countries, and is responsible for more deaths than all forms of cancer combined.
In the U.S., over half of the adult population has undesirably high serum cholesterol levels. For instance, 59 million American adults (32 percent) have blood cholesterol levels from 200 to 239 mg/dL (termed mild hypercholesterolemia), and about 38 million adults (21 percent) have serum cholesterol levels of 240 or above (termed severe hypercholesterolemia).
The amount of cholesterol obtained from diet for adult humans (especially from egg yolks, meat, poultry, fish, seafood and whole milk dairy products) is typically 350 mg daily, and another 800 mg are synthesized. It is generally accepted that high levels of cholesterol in the human diet can result in a rise in serum cholesterol and thereby increases the risk of cardiovascular diseases such as atherosclerosis, myocardial infarction, and hypertension. Therefore, medical practitioners recommend a reduced dietary intake of cholesterol (less than 300 mg/day) for all Americans (National Institutes of Health Consensus Development Panel).
Animal products, such as poultry, eggs, meat, and whole-milk dairy products, are recognized as excellent sources of dietary protein, minerals and other nutrients. However, health professionals recommend limited intake of these animal products due to their high content of cholesterol and fat. Cholesterol is present on average in amounts ranging from 70-150 mg per 100 g edible portion for beef (125 mg/100 g), calf (120), pork (90), turkey (80), duck (70), chicken (110), and shrimp (150). Chicken egg yolks have the highest cholesterol content of commonly-eaten foods (1330 mg/100 g).
As a result of the need to lower serum cholesterol in a general adult population with a diet high in cholesterol-rich foods, research and development efforts have been directed to low cholesterol foods, which the FDA defines as foods that are physiologically hypocholesterolemic (such as oatmeal, for example) that can provide both basic nutrition and may prevent coronary heart disease.
One area of research known in the art has been efforts to develop low cholesterol eggs, a highly nutritious but also high-cholesterol foodstuff. These efforts have been primarily directed at developing a low cholesterol, intact chicken egg, and include genetic selection, use of low fat and high fiber diets, and various egg selection methods. Of these, dietary measures are the most widely attempted methods, while the other methods are both technically difficult and time-consuming. However, there has been little success in the art in producing a low cholesterol egg regardless of the method employed.
An alternative to these methods for reducing the cholesterol content of domestic animal products is administration of pharmacological cholesterol-reducing agents known in the art to be useful in reducing serum cholesterol in humans. The most effective hypocholesterolemic agents for the treating hypercholesterolemia in current use for humans is the group of compounds, called statins, which inhibit cholesterol biosynthesis by inhibiting the key rate-limiting enzyme known as 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMG-CoA reductase). It is known that certain mevalonate derivatives inhibit the biosynthesis of cholesterol by inhibition of HMG-CoA reductase (Hulcher, 1971, Arch. Biochem. Biophys. 146: 422). The first such hypocholesterolemic compound discovered was compactin, also known as ML236B or mevastatin, which was isolated from cultures of Penicillium. Thereafter, a hypocholesterolemic compound found to be structurally related to compactin was isolated in fermentation products of several fungal species, including species from the Monascus and Aspergillus genera (Endo, 1979, J. Antibiot. 32: 852; Alberts et al., 1980, Proc. Natl. Acad. Sci. USA 77: 3957). The isolated active compounds (known as lovastatin, mevinolin, monacolin K, mevacor, MB530B, MK-803, or MSD803), their derivatives, methods of purification from several genera, and methods of semi-synthetic production from these derivatives have been reported in the art.
U.S. Pat. No. 3,983,140 discloses preparation of compactin (ML236B) from the genus Penicillium, preferably of the strain P. citrinum (strain ATCC 38065, ATCC 20606, SANK 18767).
U.S. Pat. No. 4,049,495 discloses preparation of compactin (ML236B) from the genus Penicillium, preferably of the strain P. citrinum (strain ATCC 38065, ATCC 20606, SANK 18767).
U.S. Pat. No. 4,231,938 discloses preparation of lovastatin (MSD803) from the genus Aspergillus, preferably A. terreus (ATCC 20541 and ATCC 20542) U.S. Pat. No. 4,294,846 discloses preparation of antihypercholesterolemic compounds from Aspergillus species.
U.S. Pat. No. 4,294,926 discloses preparation of lovastatin (MSD803) from Aspergillus terreus. 
U.S. Pat. No. 4,319,039 discloses methods for isolating antihypercholesterolemic compounds from Aspergillus terreus. 
U.S. Pat. No. 4,323,648 discloses preparation of lovastatin (monacolin K) from the genus Monascus, preferably M. anka (IFO 6540 or SANK 10171), M. ruber (ATCC 20657, SANK 10671, SANK 15177, SANK 18174, SANK 13778), M. purpureus (ATCC 16365, ATCC 16427, IFO 4513 or SANK 10271), M. vitreus (SANK 10960) and M. paxii (IFO 8201 or SANK 11172).
U.S. Pat. No. 4,342,767 discloses preparation of antihypercholesterolemic compounds from Aspergillus species.
U.S. Pat. No. 4,346,227 discloses derivatives of the antihypercholesterolemic compound ML236B.
U.S. Pat. No. 4,351,844 discloses preparation of lovastatin from the genus Monascus. 
U.S. Pat. No. 4,361,515 discloses preparation of lovastatin from the genus Monascus. 
U.S. Pat. No. 4,376,863 discloses preparation of lovastatin from the genus Aspergillus, preferably A. terreus. 
U.S. Pat. No. 4,420,491 discloses preparation of antihypercholesterolemic compounds from Aspergillus species.
U.S. Pat. No. 4,432,996 discloses preparation of antihypercholesterolemic compounds from the genus Penicillium. 
U.S. Pat. No. 4,444,784 discloses preparation of antihypercholesterolemic compound derivatives from Aspergillus terreus. 
U.S. Pat. No. 4,450,171 discloses preparation of antihypercholesterolemic compound derivatives from Aspergillus terreus. 
U.S. Pat. No. 4,739,073 discloses intermediates for synthesis of mevalonolactone antihypercholesterolemic compounds.
U.S. Pat. No. 5,362,638 discloses preparation of lovastatin from the genetically engineered strain of A. oryzae (ATCC 74135).
U.S. Pat. No. 5,403,728 discloses preparation of lovastatin from the genus Aspergillus, preferably A. terreus (ATCC 20541 and ATCC 20542) and A. obscurus (NCAIM(P)F 001189).
U.S. Pat. No. 5,712,130 discloses preparation of lovastatin from the genetically engineered strain of A. oryzae (ATCC 74135).
U.S. Pat. No. 6,046,022 discloses preparation of hypocholesterolemic compounds from the genus Monascus, employing red rice fermentation products.
U.S. Pat. No. 6,165,757 discloses preparation of lovastatin from the genus Monascus. 
U.S. Pat. No. 6,197,560 discloses preparation of lovastatin from the genus Monascus. 
U.S. Pat. No. 6,268,186 discloses preparation of lovastatin from the genus Monascus. 
British Patent Specification No. GB 2,046,737 discloses preparation of antihypercholesterolemic compounds from Monascus. 
British Patent Specification No. GB 2,049,664 discloses preparation of antihypercholesterolemic compounds from Monascus. 
British Patent Specification No. GB 2,055,100 discloses preparation of antihypercholesterolemic compounds from Monascus. 
German Patent No. DE 3,051,175 discloses preparation of antihypercholesterolemic compounds from Monascus. 
German Patent No. DE 3,051,099 discloses preparation of antihypercholesterolemic compounds from Monascus. 
German Patent No. DE 3,006,216 discloses preparation of antihypercholesterolemic compounds from Monascus. 
German Patent No. 4,402,591 discloses preparation of lovastatin by microorganisms belonging to the Pleurotus genus, preferably P. ostreatus, P. sapidus and P. saca, 
Canadian Patent No. 2,129,416 discloses the preparation of lovastatin with a microorganism belonging to the Coniothyrium genus, preferably Coniothyrium fuckelii (ATCC 74227).
Hungarian Patent No. HU 208,997 discloses preparation of lovastatin from the genus Aspergillus, preferably A. terreus (ATCC 20541 and ATCC 20542) and A. obscurus (NCAIM(P)F 001189).
Other microorganisms capable of producing hypocholesterolemic compounds are known in the art, include species from the genera Paecilomyces, Hypomyces, Doratomyces, Phoma, Eupenicillium, Gymnoascus, and Trichoderma (Juzlova et al., 1996, J. Indust. Micro. 16: 163; Endo et al., 1986, J. Antibiotics 39: 1609; Sutherland et al., 2001, Curr. Opin. Drug Discov. Devel. 4: 229; U.S. Pat. No. 5,409,820; German Pat. No. 4,402,591). Statin-producing microorganisms or other hypocholesterolemic compound-producing microbial strains can be naturally occurring, genetically engineered, or altered from the wild type (such as mutant strain, for example Paecilomyces sp. M2016, Phoma sp. M4452, Trichoderma longibrachiatum M6735, and Trichoderma pseudokoningii M6828).
Using microorganisms capable of producing hypocholesterolemic compounds, several statins have been developed as HMG-CoA reductase inhibitors for the treatment of hypercholesterolemia. These include mevastatin (disclosed in U.S. Pat. No. 3,983,140), lovastatin or mevinolin (disclosed in U.S. Pat. No. 4,231,938), pravastatin (disclosed in U.S. Pat. No. 4,346,227), simvastatin (also referred to as synvinolin; disclosed in U.S. Pat. Nos. 4,444,784 and 4,450,171), fluvastatin (disclosed in U.S. Pat. No. 4,739,073), atorvastatin (disclosed in U.S. Pat. No. 5,273,995) and derivatives of these compounds. These compounds are highly active hypocholesterolemic agents and are available as prescription drugs: Atorvastatin (Lipitor; Pfizer), Fluvastatin (Lescol; Novartis), Lovastatin (Mevacor; Merck), Pravastatin (Pravachol; Bristol-Myers Squibb) and Simvastatin (Zocor; Merck).
In addition to prescription drugs, alternative sources of cholesterol-lowering dietary supplements include red yeast rice, which is the fermentation product of rice on red yeast, or cultures of lovastatin-producing Monascus purpureus. It is known that consumption of red yeast rice can reduce cholesterol concentration significantly in humans. Curiously, the quantities of lovastatin in red yeast rice are inadequate to explain the magnitude of the lowering of cholesterol observed when compared with lovastatin treatment (Herber et al., 1999, Am. J. Clin. Nutr. 69: 231-236). The cholesterol-lowering effect of red yeast rice is unlikely to result solely from the lovastatin contained in either red yeast or Monascus; it could result from a combination of additional, unidentified hypocholesterolemic compounds (if any) contained in the red yeast rice fermentation, but there have been no reports in the art concerning such putative additional hypocholesterolemic compounds.
Recently, significant reduction of the cholesterol content of egg yolk was demonstrated by oral administration of purified lovastatin to chickens (Elkin and Rogler, 1990, J. Agric. Food Chem. 38: 1635-1641, 1990; Elkin et al., 1993, J. Agric. Food Chem. 41: 1094-1101; U.S. Pat. Nos. 6,177,121 and 6,316,041). Although the cholesterol-lowering effect was found to be satisfactory when the egg-laying chickens are fed high doses of lovastatin, use of these methods are impractical due to the high production cost of effective amounts of HMG-CoA reductase inhibitor and consequently high production cost of low cholesterol eggs.
Thus, inexpensive and effective methods for producing animal products having lower than naturally-occurring cholesterol levels, resulting in the production of low cholesterol foods are needed in the art. Furthermore, as illustrated with red yeast rice, methods for improving cholesterol lowering effect of animal feed on animal-derived foodstuffs by employing complete fermentation products rather than a single isolated species from the fermentation products are needed in the art.